How to use enqueu, dequeue, push, and peek in a Palindrome? - c++

Question

I'm writing a program to see if a string is a palindrome. I'm having trouble with the implementing the queue.enqueue(nextCharacter), stack.push(nextCharacter), queueFront = queue.peekFront(), stackTop = stack.peek(), queue.dequeu(). I tried looking at examples online of implementations of peek(), deque, push, and enqueue. Could not find any that worked correctly. I have to follow this exact format of this program.
// Start of Pseudcode given:
isPalindrome(someString: string): boolean
{
// Create an empty queue and stack
aQueue = new empty queue
aStack = new empty stack
// Add each character of string to both queue and stack
length = length of someString
for (i= 1 throught length)
{
nextChar = ith character of someString
aQueue.enqueue(nextChar)
aStack.push(nextChar)
}
charactersAreEqual=true
// Compare queue characters with stack characters
while (aQueue is not empty and charactersAreEqual)
{
queueFront = aQueue.peekFront();
stackTop = aStack.peek()
if(queueFront equals stackTop)
{
aQueue.dequeue();
aStack.pop()
}
else {
charactersAreEqual = false
}
#include <string>
#include <queue>
#include <stack>
#include <iostream>
bool isPalindrome(std::string str) {
// Declare variables
int length;
char nextCharacter;
bool charactersEqual;
char queueFront;
char stackTop;
// Create an empty queue and stack
std::queue<char> queue;
std::stack<char> stack;
// Set lenth to length of string
length = str.length();
// Add each character of string to both queue and stack
for (int i = 0; i < length; i++) {
nextCharacter = str.at(i);
queue.enqueue(nextCharacter); // ??????
stack.push(nextCharacter); // ?????
}
// Set characters to true
charactersEqual = true;
// Compare queue characters with stack characters
while (!queue.empty() && charactersEqual) {
queueFront = queue.peekFront(); // ?????
stackTop = stack.peek(); // ?????
if (queueFront == stackTop) {
queue.dequeu(); // ?????
stack.pop();
}
else {
charactersEqual = false;
}
}
return charactersEqual; // return characters that are equal
}

Answer 1

For an ASCII string, you can:
bool result = std::equal(str.begin(), str.end(), str.rbegin(), str.rend());
If you are using Unicode then you should probably reverse the whole string then use the equality operator:
bool isPalindrome(std::u8string str)
{
// Less efficient
std::u8string rstr{str};
std::reverse(rstr.begin(), rstr.end());
return (str == str2);
}
For instance, is 'é' and 'e' the same letter? In Dutch, "één hond" and "een hond" are the same because the first means "one dog" and the second can mean either "one dog" or "a dog" depending on the context. Therefore, you need to be careful if you need internationalization.

Answer 2

Here's a snippet from a program I wrote a while ago that checks if a word is a palindrome. I know it's not what you're asking for, but I figured I'd put it out there.
bool isPalindrome(const string word)
{
for (int i = 0, j = word.length() - 1; i < j; i++, j--)
{
if (word[i] != word[j]) //If any comparison fails, return false
return false;
}
//If all the checks passed, return true
return true
}